Fluidized Bed Heat Exchanger Tube Support Design

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Solution Overview

Problem

Existing circulating fluidized bed boiler designs face issues with tube support systems, including local vibrations, abrasions, and installation complexities due to gaps and wearing associated with sliding connections, and the difficulty in ensuring proper alignment without high construction skills.

Innovation Solution

A boiler design featuring a fluidized bed heat exchanger with at least two vertical supports for each tube, where horizontal portions of the boustrophedon path are linked by vertical portions, with one supporting device on each side of the tube bundle, allowing for differential movement and reduced bending stresses by alternating fixation points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If sliding connections with supports are used to allow differential movements between tubes and supports, then differential movement is enabled, but gaps and wearing occur leading to local vibrations and abrasions

Engineering Contradiction:
Improvedifferential movement capabilityVSAvoidvibration and abrasion resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention extracts the problematic sliding connection interface by replacing it with a direct fixed connection between tubes and supports. The differential movement capability is achieved not through sliding but through the flexibility of the tube bundle itself and the arrangement of multiple supports, eliminating the source of gaps and wearing.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using durable but complex sliding connections that wear over time, the invention employs simple fixed connections that are easier to maintain and replace if needed, prioritizing simplicity and reliability over long-term durability without maintenance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If shims are used to ensure proper alignment, then alignment precision is improved, but installation complexity and construction skill requirements increase

Engineering Contradiction:
Improvealignment precisionVSAvoidinstallation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The support structure is designed to be self-aligning through its geometric configuration. The multiple vertical supports arranged in a specific pattern automatically provide proper alignment for the tubes without requiring shims or highly skilled installation work. The system serves itself by design rather than requiring external adjustment tools or expertise.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the installation parameters by using a standardized grid pattern of supports with fixed spacing and positioning. This transforms the alignment problem from one requiring skilled judgment and shim adjustment to one solved by simple geometric replication and standardization.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If multiple vertical supports are used to fix tubes, then local vibrations and abrasions are prevented, but device complexity increases

Engineering Contradiction:
Improvevibration and abrasion resistanceVSAvoidsupport structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The support structure is segmented into multiple independent vertical supports distributed along the tube bundle. Each support handles a localized section, preventing vibrations and abrasions at specific points without requiring a complex integrated support system. The segmentation allows simple modular construction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from considering support as a single-dimensional problem (one support per tube) to a two-dimensional grid pattern (multiple supports per tube bundle). This dimensional change distributes the support function across space, reducing local vibrations without requiring overly complex individual support elements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design effectively prevents local vibrations and abrasions, simplifies installation by distributing effort, and reduces bending stresses, enhancing the stability and reliability of the fluidized bed heat exchanger.

Implementation Method 1

Heat exchanger elements, often in the form of tube coils following a boustrophedon path, are located inside this fluidized bed and are fed with a coolant fluid

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

hot solids are brought into a chamber, in which they are fluidized with air or re-circulated flue gas as a slowly bubbling fluidized bed

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

every vertical supporting device comprises at least two vertical supports for fixing the tubes, typically at least two separate vertical supports. Thus, the fixation of the tubes on the vertical supports prevents local vibrations and possible abrasions resulting therefrom. Using at least two supports by device makes it possible to split the amount of efforts

Methodology Applied
Scientific EffectMechanical stress distribution:

Data Source

PatentEP2735791B1Boiler having a fluidized bed heat exchanger
Publication Date: 2015.07.29 ALSTOM TECH LTD
  • EP2735791B1 patent drawingFigure 1~2
  • EP2735791B1 patent drawingFigure 3~4
  • EP2735791B1 patent drawingFigure 5~6

AI summary

The invention relates to a fluidized bed heat exchanger (3A), the heat exchanger (3A) including a plurality of tubes (7) forming a tube bundle, each tube (7) following a vertical boustrophedon path, the tubes (7) being supported by at least two vertical supporting devices (41,42) placed on both sides of the tube bundle, characterized in that every vertical supporting device (41,42) comprises at least two vertical supports (411,412;421,422) for fixing the tubes (7).